(a) Field of the Invention
The present invention relates to an apparatus and a method for controlling an engine clutch.
(b) Description of the Related Art
As is generally known in the art, a hybrid vehicle uses an internal combustion engine and battery power supply together. In other words, the hybrid vehicle uses a combination of torque of the internal combustion engine and torque of a motor. In general, the hybrid vehicle includes an engine, a motor, an engine clutch configured to adjust torque between the engine and the motor, a transmission, a differential gear device, a high voltage battery, a hybrid starter & generator (HSG) configured to start the engine or generate power based on an output of the engine, and wheels. The HSG may refer to an integrated starter & generator (ISG).
The hybrid vehicle is capable of being driven in an electric vehicle (EV) mode in which torque of a motor is used by engaging or releasing (e.g., disengaging) the engine clutch based on acceleration or deceleration intention according to a manipulation of an accelerator pedal and a brake pedal, a vehicle speed, a state of charge (SOC) of the battery, and the like; a hybrid electric vehicle (HEV) mode in which torque of the engine is used as main power and torque of the motor is used as auxiliary power; and a regenerative braking mode in which braking and inertial energy are recovered through electrical power generation of the motor during braking the vehicle or during driving of the vehicle by inertia to be charged in the high voltage battery. Since the hybrid vehicle uses both of mechanical energy of the engine and electrical energy of the battery, uses optimal operation regions of the engine and the motor, and recovers the energy upon braking, fuel efficiency may be improved and the energy may be efficiently used.
In the method for controlling the engine clutch according to the related art, when the EV mode is switched to the HEV mode (i.e., when the engine starts), after engine speed is synchronized to motor speed, drivability may be ensured to prevent engagement shock from occurring while torque is delivered between an engine and a motor which are different torque sources by engaging an engine clutch. In particular, a target speed of the engine (i.e., target speed of an input shaft of the engine clutch) is generated based on motor speed (i.e., speed of an output shaft of engine clutch) using a filter, and the engine speed is adjusted to track (e.g., to correspond to) the target speed. However, as shown in FIG. 7, when the target speed of the engine is time-varied or a disturbance occurs, precise control may be difficult using the method for operating the engine clutch according to the related art. Therefore, overshoot of the engine speed may occur, a time required to engage the engine clutch is increased, and engagement shock may occur.
The above information disclosed in this section is merely for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.